That's strange!!

^Which one is by default highlighted?? If it's WinXP then try by changing the value of timeout from 30 to 0. It will not show the menu as the time for displaying it is changed to 0 seconds!!
Or take a loot at this: *www.tech-recipes.com/rx/1040/vista_how_to_uninstall_vista_dual_boot_machine/
And this
*www.ditii.com/2009/01/28/how-to-modify-windows-7-boot-loader/